A highly emissive distyrylthieno[3,2-b]thiophene based red luminescent organic single crystal: Aggregation induced emission, optical waveguide edge emission, and balanced ambipolar carrier transport

A highly emissive red luminescent single crystal which shows aggregation induced emission (AIE) property and optical waveguide edge emission based on small organic functional molecule, cyano-substituted 2,5-di((E)-styryl)thieno[3,2-b]thiophene (CNP2V2TT) has been prepared by the physical vapor transport (PVT) method. The fluorescence quantum efficiency of crystal is up to 37% and an emission peak maximum (λ_max) locates at 645 nm. Cystallographic data indicate that uniaxially oriented molecular packing with slipped face-to-face π-π stacking forms by the hydrogen bonding network among CNP2V2TT molecules. The single crystal FET devices were fabricated using Au and Ca as hole and electron injection electrodes, respectively. The molecular design, introducing cyano groups into molecular skeleton, effectively lower the LUMO level and achieve well-balanced ambipolar electron (0.13 cm² V^-1 s^-1) and hole (0.085 cm² V^-1 s^-1) mobilities.